If at any stage of the booking you want to stop and continue on at a later time, you can park your booking. Click on the park booking button. If you choose to do this a window will appear asking for a title and/or a description of what the booking is, type in the key number as the title and then click ok.
To resume your parked booking, you will see a link under the glance panel at the opening page. It will say you have 1 parked booking click on this link and then select from the window displayed which booking you want to continue with, then click the load button and continue with the booking.